Spoken document representations for probabilistic retrieval

This paper presents some developments in query expansion and document representation of our spoken document retrieval system and shows how various retrieval techniques affect performance for different sets of transcriptions derived from a common speech source. Modifications of the document representation are used, which combine several techniques for query expansion, knowledge-based on one hand and statistics-based on the other. Taken together, these techniques can improve Average Precision by over 19% relative to a system similar to that which we presented at TREC-7. These new experiments have also confirmed that the degradation of Average Precision due to a word error rate (WER) of 25% is quite small (3.7% relative) and can be reduced to almost zero (0.2% relative). The overall improvement of the retrieval system can also be observed for seven different sets of transcriptions from different recognition engines with a WER ranging from 24.8% to 61.5%. We hope to repeat these experiments when larger document collections become available, in order to evaluate the scalability of these techniques.

Security considerations in the design and peering of RFID discovery services

There is growing interest in Discovery Services for locating RFID and supply chain data between companies globally, to obtain product lifecycle information for individual objects. Discovery Services are heralded as a means to find serial-level data from previously unknown parties, however more realistically they provide a means to reduce the communications load on the information services, the network and the requesting client application. Attempts to design a standardised Discovery Service will not succeed unless security is considered in every aspect of the design. In this paper we clearly show that security cannot be bolted-on in the form of access control, although this is also required. The basic communication model of the Discovery Service critically affects who shares what data with whom, and what level of trust is required between the interacting parties. © 2009 IEEE.